(81b) Low Temperature Catalytic GASIFICATION of BIOMASS for Syngas and Chemicals PRODUCTION

Traditional gasification of biomass feedstocks occur a high temperatures because of the refractive tars that do no easily crack. We investigated the catalytic conversion of biomass feedstocks into gaseous products and phenolic liquids. Biomass feedstocks (pine, polar, switchgrass and corn stover) were pyrolyzed in a bubbling fluidized bed reactor using ZSM5 catalysts. The results showed that most of the carbohydrate fractions were gasified at 400-450 oC into CO, CO2, C1 to C4 hydrocarbons whereas the liquid fraction was mostly aromatic compounds. The liquid product yield was low, ranging from 25-35%, the char yield ranged from 15-25% and the difference was gas. The yield of various products was feedstock dependent.

The viscosity of the liquid fraction was much lower than that of conventional biomass pyrolysis oil and its pH was higher than that of conventional pyrolysis oil. The catalytic pyrolysis oil did not age as fast as conventional pyrolysis oil especially with respect to increase in viscosity with time. The higher heating value of the catalytic pyrolysis oil was also higher than that of the conventional pyrolysis oil. Fractionation of the liquid product showed that 54-70% was phenolic, 2-10% was aliphatic hydrocarbons, and 2-5% was polycyclic aromatic hydrocarbons (PAH). The relative yield of the fractions was also feedstock dependent. Switchgrass catalytic pyrolysis oil fraction was richer in hydrocarbon fraction compared to the woody biomass feedstocks.